Method for the preservation of wooden structures



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15?.31 as i is alt-restate ,5 p f a heated Dec. 20, 1960 a pole withcreosote and pentachlorophenol does not aid in the protection of thepole from fire since the cracks, 2 965 516 crevices and pole surfaceessentially remain exposed and METHOD FOR THE PRESERVATION OF WOODENSTRUCTURES Clarence E. Wilkinson, Port Neches, Tex., assignor to TexacoInc., a corporation of Delaware No Drawing.

This in ention is concerned with a novel method employing a novelcomposition for protecting and preserving wooden structures such asmarine pier piles and utility poles from the action of bacteria andfungi and from the effects of fire, moisture and weathering.

The novel composition of this invention has a combination of propertieswhich makes it an economical and effective wooden structurepreservative, viz.

(1) Low cost.

(2) Ready penetration of wood fiber on the surface, for example, whereoriginal creosote has been leached out.

(3) Excellent adhesives to wood surfaces.

' (4) Arresting wood decay, if started, and prevention of same if woodis fresh.

(5) Fire resistance, and

(6) A composition consistency so balanced that it can be rapidly forcedinto checks, pockets and cracks of wooden structures by ordinary spraygun techniques and then stay put without substantial sagging to providea usefully heavy coat.

The novel method of this invention provides a simple, efiectiye and lowcost means for substantially extending the life of wooden structures,particularly utility poles. More specifically, it has been found throughthe use of rny-novel method the maintenance and replacement of woodenstructures can be reduced to a minimum without jeopardizing theoperation of such structures. The method permits wooden surfaces areaswhether large or small to be rapidly treated (e.g. by painting orspraying) using a small labor crew and provides an adherent protectivecoating which substantially prevents atmospheric weathering, decay anddamage by fire.

This application is a continuation-impart of co-pending application,SerialNo. 430,401, filed May 17, 1954, now abandoned.

Wooden polesare commonly treated with creosote for the purpose ofpreserving the wood and in addition to the creosote, the'polcs are oftenpainted with some fungitoxic material such as pen-tachlorophenol. Suchprotection means for the poles is generally satisfactory in protectingthe wood from the effects of weathering except at about the earthsurface level and below. At this point the decay of the wood haspresented a serious problem. It appears that the ground water and/orearth surface water leaches the creosote and the pentachlorophenol fromthe wood; the bacteria and fungi in the soil and/or I water then attackthe wood. Such decay has been found in many instances to more than halvethe life expectancy of wooden poles.

In addition to the problem of decay, wooden poles are prone to damage byfire. This is accentuated by th; numerous cracks and crevices generallyextending from the pole surface deep into the interior. These cracks andcrevices when located in the area of the pole above the earth surfacelevel .act as chimneys for fire and form excellent beds for the lodgingof sparks from neighboring fires, e.g. grass fires. The end result ofthe lodging of these sparks is often a damaging pole fire. Coatingfurthermore, creosote, being a good combustible material, aids ratherthan hinders the propagation of fire.

In accordance with the invention, it has been discovered that by theapplication of my novel asphalt base composition containing a particularfungitoxic agent which is readily dispcrsible and capable of retentionin the asphalt base under weathering and in the presence of moisture,the attack on the wood by bacteria and fungi can be effectivelyprevented. In addition, my novel composition upon application to thepoles and with curing forms an efiective fire resistant coating. Theignition of the pole by sparks or flames from neighboring fires isdiscouraged for all the cracks and crevices are plugged and the polesurface is insulated by an adherent fire resistant asphaltic coatingwhich forms an essentially smooth continuous surface.

The fungitoxic agent employed in my novel composition iscopper-S-quinolinolate. It has been discovered that this compound isreadily dispersible in the asphaltic composition and has a dispersioncoetficient as between asphalt and water that is favorable to itsretention in the former. In addition, copper-S-quinolinolate has beenfound to be stable at the relatively high temperatures needed tocompound the asphaltic composition most economically.

The novel composition includes a suitable asphalt base cut back with arelatively light hydrocarbon distillate such as naphtha or kerosene. Thecomposition also contains a quantity of asbestos filler. It has beenfound asbestos is an excellent material for arting the desired body andstrength as well as fire resistant properties to the composition.

When applying the composition to utility poles in service, the soil isremoved from about the pole for a depth of say l-2 feet or more. Thepole is cleaned of any loose or decayed wood. If desired, a fungitoxicmaterial such as pentachlorophenol or tetrachlorophenol solution may befirst applied to the pole. The asphalt cutback composition of theinvention containing copper-S-quinolinolate and asbestos is then appliedwith a brush or preferably sprayed on the pole with a spray gun so as tocover it for a distance of from about one foot or more below to wellabove the earth surface level. A good thick coating is applied such as/s-Mi inch in thickness. The treated section of the pole, may, ifdesired, be covered with an asphalt saturated felt. This givesadditional pro tection although adequate protection has been obtainedwithout this extra precaution. In applying the composition to polesprior to being installed, the pole is coated in the above manner overthat section of the pole for which protection is desired.

The asphalt component of the protective composition consists of a goodcoating asphalt such as an asphalt prepared from parafiinic-asphaltic orasphaltic-cyclic crude petroleum residuum by steam or a vacuumdistillation and/or air blowing. A suitable asphalt will have asoftening point of about -180 ball and ring, a penetration at 77 F. ofabout 30-60 and a solubility in carbon tetrachloride of at least about99.5 weight percent (wt. percent). The asphalt is mixed with a lightdistillate such as naphtha and kerosene. The proportions of the asphaltcutback in the totalmixture will be about 65-85 wt. percent. The amountof asphalt and volatilizable diluent comprising the cut-back will varydepending upon the consistency of the cutback desired but ordinarily theproportions will approximate 50-70 volume percent (vol. percent) ofasphalt and 50-30 vol. percent ofdistillate. The volume percent is basedon the total volume of the cutback.

I f i The cutback is mixed with asbestos fibers in proportions to yielda good plastic mixture capable of being applied to the wood. Theasbestos content will ordinarily be within a range of 15-30 wt. percentof the total mixture. In using asbestos as the tiller, it is consideredbest to use fine asbestos in the mixture, e.g. substantially passing a12 mesh U.S. standard screen, although it may be advantageous to use asmall proportion of coarse asbestos, eg. substantially all retained on a12 mesh U.S.-standard screen. These grades of asbestos are well known inthe market, thus, for example, .lohns-Manville Corp. markets a fineasbestos as grade 7M and a coarse asbestos as grade 7D. Asbestos Corp.markets a fine asbestos as grade 7R.

The fungitoxic agent, copper-8-quinolinolate, is preferably added to thecutback prior to incorporating the asbestos. The copper-8-quinolinolateis available as a fine powder and it is advantageous to disperse it in asmall amount of hydrocarbon such as kerosene and then add the dispersionto the cutback. Very small proportions of this fungitoxic agent arerequired. Surprisingly, it has been discovered thatcopper-S-quinolinolate is even more toxic at low concentrations than athigher concentrations in my composition. For example, in some cases 1wt. percent concentration was found to be more effective than a wt.percent concentration. More particularly, concentrations of betweenabout .05 to 5 wt. percent have been found effective with concentra-'tions between about 0.09 and 1 wt. percent being preferable. The wt.percent of copper-8-quinolinolate is based on the total mixture.

In an example of the invention, a composition was prepared consisting of75 wt. percent cutback, 22.5 wt. percent fine asbestos and 2.5 wt.percent coarse asbestos. The cutback consists of 56.7 vol. percentasphalt, 43.3 vol. percent kerosene and had a viscosity of 164 at 122 F.Saybolt Furol. Copper-S-quinolinolatc was added in an amount of 0.2 wt.percent of the cutback. After removal of the soil for a distance abouteach of several utility poles in service and removing any loose ordecayed wood therefrom, the asphalt composition was sprayed on a sectionof each pole to a thickness of about Vs-l inch beginning at a pole about2% feet below ground level and extending about 1% feet above. Thecoating was allowed to set, after which the dirt around the hole wasreplaced. After a considerable period of time, the coating was strippedOE and no evidence of bacterial, fungal or moisture attack of the coatedarea of the poles was found. There was definite evidence of such attackon an uncoated pole used as a control. In some cases where it wasnecessary to back-fill around a pole immediately after the coating wasapplied, an asphalt saturated felt was wrapped around the coated pole.The coating, both with and without the asphalt felt, has proved highlysatisfactory in protecting the poles.

In another example of the invention which emphasizes the excellent fireresistance of my novel composition as well as the novel method ofprotecting wooden poles from damage by neighboring fires, a compositionwas prepared consisting of 77 wt. percent cutback, 22.9 wt. percent fineasbestos and 0.1 wt. percent copper-8- quinolinolate. The cutbackconsisted of 62.0 vol. percent asphalt, 38 vol. percent kerosene and hada viscosity of 110 at 122 F. Saybolt Furol. The asphaltic compositionwas applied on the section of a utility pole to a thickness of V8% inchbeginning at a point at the ground level and extending approximately 7feet thereabove. It was observed the cracks and crevices in the polewere readily filled during the application operation. The coating wasallowed to cure for 8 weeks. At the end of that period of time hay wasstacked around the coated pole up to a height of 7 feet Strings weretied around the stack of hay to hold it in place. The hay .was thenignited at a point about 2 feet from the top of the stack on thewindward side. Wind velocity at that time was about 10-15 miles/hr. Theflames spread rapidly around the pole burning the string which permittedthe burning hay to slide down the stack to the ground. Then the coatedpole was engulfed in a very hot fire which, under the force of the wind,channeled up the pole a distance of 10-12 feet on the leewardside. Flameduration was 6-10 minutes. In a subsequent examination of the section ofthe pole underneath the asphaltic coating no evidence of charring wasfound and the coating itself remained substantially whole. The uncoatedsection of the pole exposed to the flames was severely charred.

The fire protection feature of the invention, of course, does not dependupon the presence of a copper-8-quinolinolate and therefore if fireprotection is primarily desired and decay is not a problem, thequinolinolate compound may be omitted from the composition with acorresponding increase in the minimum quantity of asphalt cutbackcomponent from about wt. percent to about wt. percent.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated in the appended claims.

claim:

1. A method of protecting from moisture, bacteria, fungi and fire awooden structure containing cracks and crevices therein comprisingfilling said cracks and crevices and coating the exterior surface ofsaid structure with a compo s itihn consisting essentially of about.05-5 wt. percent oopper-8-qu ip c lip ol ate, about 15-30 wt. percentasbestos, and about 65-85 wt. percent asphalt cutback,

said cutback consisting essentially of 50-70 vol. percent asphalt and30-50 vol. percent volatilizable diluent.

2. A composition in accordance with claim 1 wherein saidcopper-S-quinolinolate is present in an amount of about 0.09 to 1 wt.percent.

References Cited in the file of this patent UNITED STATES PATENTS1,883,683 Gardner ct al. Oct. 18, 1932 2,054,285 Foster Sept. 15, 19362,396,910 Zaisser Mar. 19, 1946 2,552,947 Pasold et al. May 15, 19512,569,399 Burns et al Sept. 25, 1951 2,580,025 Holmes Dec. 25, 19512,608,556 Kalbert Aug. 26, 1952 2,738,286 Greider et a1 Mar. 13, 1956OTHER REFERENCES Eisenschiml et al.: Ofiicial Digest (December 1948),pp. 953-962.

UNITED STATES PATENT @FHCE CER'llICATlN I ECWN Patent No'-., 2 965516December 2O 1960 Clarence" E, Wilkinson It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 1 line 42 for "surfaces" read surface column 3 line 6 after"substantially insert we all column 4 line 4'1 for composition" readmethod Signed and sealed this 23rd day of May 1961;,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

1. A METHOD OF PROTECTING FROM MOISTURE, BACTERIA, FUNGI AND FIRE AWOODEN STRUCTURE CONTAINING CRACKS AND CREVICES THEREIN COMPRISINGFILLING SAID CRACKS AND CREVICES AND COATING THE EXTERIOR SURFACE OFSAID STRUCTURE WITH A COMPOSITION CONSISTING ESSENTIALLY OF ABOUT .05-5WT. PERCENT COPPER-8-QUINOLINOLATE, ABOUT 15-30 WT. PERCENT ASBESTOS,AND ABOUT 65-85 WT. PERCENT ASPHALT CUTBACK, SAID CUTBACK CONSISTINGESSENTIALLY OF 50-70 VOL. PERCENT ASPHALT AND 30-50 VOL. PERCENTVOLATILIZABLE DILUENT.